The present invention relates to a heddle frame for a loom, and in particular to an improved heddle frame having a center brace for maintaining parallelism between the top and bottom rails of the heddle frame.
A known heddle frame with an improved center brace assembly is disclosed in U.S. Pat. No. 4,924,916. In this patent, the heddle frame comprises top and bottom rails which are typically made of extruded aluminum, as commonly understood in the art. The top and bottom rails are connected to each other at their ends by end struts or members to provide a rigid connection between the rails and to define a generally rectangular harness or heddle frame. The frame includes top and bottom heddle supporting rods or rails upon which the heddles are slidably mounted, as is commonly understood in the art. A center brace is mounted midway between the ends of the frame, and in some cases a plurality of braces may be employed. The center brace serves to prevent distortion of the frame and to maintain the parallel relationship between the top and bottom rails.
In the '916 patent, the center brace extends through an opening into the top rail and into an opening in the bottom rail. A top sleeve is disposed in an opening in the top rail and extends about the center brace to separate the brace from the opening in the top rail. Likewise, a bottom sleeve is disposed on the bottom rail and is threaded onto the center brace. Means are provided on the upper surface of the top rail to secure and retain the center brace within the opening.
U.S. Pat. No. 5,630,448 describes an embodiment of a heddle frame having a center brace assembly wherein the center brace extends between the top rail and the bottom rail. First and second locking blocks are attached to the top rail and the bottom rail and are configured to respectively receive a first flange at one end of the center brace and a second flange at the opposite end of the center brace, and to exert forces on the first and second flanges to create opposing torques thereon. This generates a torque on the center brace and thus locks the first flange and the second flange within their respective locking blocks.
U.S. Pat. No. 2,909,199 describes an early embodiment of a heddle frame incorporating a center brace assembly wherein the center brace or rod is threaded to a head piece. The head piece is seated in a recess of a member bolted to the top rail. A locking member is superposed on this recessed member. The locking member has a recess on its underside in which the head piece is positioned whereby rotation of the rod or center brace is prevented when the locking member is in its operative position.
One drawback with the known center brace assemblies is that the adjusting mechanism extends laterally beyond the width of the heddle frames and thus interferes with adjacent heddle frames. Thus, adjustment of one heddle frame is impeded by and may actually cause misalignment of adjacent heddle frames, and so forth.
The present invention provides an improved center brace assembly for heddle frames that can be vertically adjusted without interfering with adjacent heddle frames.